[PATCH 05/16] vfs: bogus warnings in fs/namei.c

[Arnd Bergmann <arnd@arndb.de>]

The follow_link() function always initializes its *p argument,
or returns an error, but not all versions of gcc figure this
out, so we have to work around this using the uninitialized_var()
macro.

Without this patch, building with arm-linux-gnueabi-gcc-4.6 results in:

fs/namei.c: In function 'link_path_walk':
fs/namei.c:649:24: warning: 'cookie' may be used uninitialized in this function [-Wuninitialized]
fs/namei.c:1544:9: note: 'cookie' was declared here
fs/namei.c: In function 'path_lookupat':
fs/namei.c:649:24: warning: 'cookie' may be used uninitialized in this function [-Wuninitialized]
fs/namei.c:1934:10: note: 'cookie' was declared here
fs/namei.c: In function 'path_openat':
fs/namei.c:649:24: warning: 'cookie' may be used uninitialized in this function [-Wuninitialized]
fs/namei.c:2899:9: note: 'cookie' was declared here

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: linux-fsdevel@vger.kernel.org
Cc: Jan Kara <jack@suse.cz>
---
 fs/namei.c |    6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/fs/namei.c b/fs/namei.c
index dd1ed1b..62a1725 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -1543,7 +1543,7 @@ static inline int nested_symlink(struct path *path, struct nameidata *nd)
 
 	do {
 		struct path link = *path;
-		void *cookie;
+		void *uninitialized_var(cookie);
 
 		res = follow_link(&link, nd, &cookie);
 		if (res)
@@ -1933,7 +1933,7 @@ static int path_lookupat(int dfd, const char *name,
 	if (!err && !(flags & LOOKUP_PARENT)) {
 		err = lookup_last(nd, &path);
 		while (err > 0) {
-			void *cookie;
+			void *uninitialized_var(cookie);
 			struct path link = path;
 			err = may_follow_link(&link, nd);
 			if (unlikely(err))
@@ -2902,7 +2902,7 @@ static struct file *path_openat(int dfd, const char *pathname,
 	error = do_last(nd, &path, file, op, &opened, pathname);
 	while (unlikely(error > 0)) { /* trailing symlink */
 		struct path link = path;
-		void *cookie;
+		void *uninitialized_var(cookie);
 		if (!(nd->flags & LOOKUP_FOLLOW)) {
 			path_put_conditional(&path, nd);
 			path_put(&nd->path);
-- 
1.7.10